Usability Technical Debt in Software Projects: A Multi-Case Study

Background: Over the years, several studies were conducted aiming at understanding the Technical Debt (TD) phenomenon and its implications on software development. Most of these studies focus on source code related TD types. The absence of empirical studies on usability debt motivated our research. Aims: The goal of this paper is to provide an initial usability debt characterization in software projects regarding its occurrence, type, and resolution effort. Method: We conducted a multi-case study, analyzing TD items of five software projects from four different companies. Results: We identified and classified 145 TD items in the projects. The analysis of these items allowed us to observe that the frequency of usability TD items ranged from 10.4% to 20.8% in the projects. The usability debt items cover a range of usability issues, violating eight out of the ten Nielsen usability heuristics. Regarding effort for paying the TD, usability debt items require a relatively low effort, ranging from 5.1% to 6.7% of the total TD resolution effort in the analyzed projects. Conclusions: Usability TD items are frequent, concern relevant usability issues and typically require low effort for their payment. Hence, paying this type of TD should receive high priority in TD management strategies.